JsonObjectMeta: Run __get_fields for each base class

.github/workflows/pytest.yml

@@ -0,0 +1,15 @@
+name: Test
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        include:
+        - os: ubuntu-latest
+
+    steps:
+    - name: Run pytest
+      uses: cclauss/GitHub-Action-for-pytest@0.5.0

pykson/__init__.py

@@ -623,9 +623,7 @@ def __get_fields(cls) -> List[Field]:
                 fields_list.append(field)
         for base in cls.__bases__:
             base_type_dicts = base.__dict__  # type(self).__dict__
-            for n, field in base_type_dicts.items():
-                if isinstance(field, Field):
-                    fields_list.append(field)
+            fields_list += JsonObjectMeta.__get_fields(base)
         return fields_list
 
     @staticmethod

test_pykson.py

@@ -0,0 +1,20 @@
+import pykson
+
+class Class1(pykson.JsonObject):
+    variable_1 = pykson.IntegerField(default_value=1)
+
+class Class2(Class1):
+    variable_2 = pykson.IntegerField(default_value=2)
+
+class Class3(Class2):
+    variable_3 = pykson.IntegerField(default_value=3)
+
+class Class4(Class3):
+    variable_4 = pykson.IntegerField(default_value=4)
+
+def test_multiple_inheritance():
+    class4 = Class4()
+    assert class4.variable_1 == 1
+    assert class4.variable_2 == 2
+    assert class4.variable_3 == 3
+    assert class4.variable_4 == 4